Panels of controllable radiation transmissivity

ABSTRACT

The invention provides a panel ( 2 ) of controllable radiation transmissivity, including a plurality of tubular cells ( 4 ), in at least some of which cells is rotatably mounted at least one radiation-blocking member ( 6 ), at least one portion of at least one surface of which is substantially opaque, and means ( 8 ) for rotating the radiation-blocking member ( 6 ) inside the tubular cells ( 4 ), wherein the radiation-blocking member ( 6 ), when rotated, is adapted, in at least one angular position, to substantially block the passage of radiation through the panel ( 2 ), and in a plurality of other, selectable, angular positions, to provide a plurality of differing radiation transmissivities.

TECHNICAL FIELD

The present invention relates to a panel of controllable radiationtransmissivity for the construction of walls, roofs, awnings, skylights,windows, and the like.

BACKGROUND ART

While panels for the above or similar purposes are known, they areeither transparent, translucent or opaque, but their transmissivity ispredetermined and cannot be altered or modified. Yet such alterabilitywould be most useful, especially in hot climates where reducedinsolation during the hot hours would reduce air-conditioning costs, orin cold climates where increased insolation would reduce heatingexpenses.

U.S. Pat. No. 5,600,920 describes a motorized louver blind structureincluding slat members operable inside a chamber formed by adouble-glazed window unit, to effect pivoting of the slats.

DISCLOSURE OF THE INVENTION

It is thus one of the objects of the present invention to provide apanel for the construction of roofs, walls, awnings, skylights, windowsand the like, the radiation transmissivity of which can be set at willto any state, from almost full transparency or translucency to almosttotal opacity.

According to the invention, the above object is achieved by providing apanel of controllable radiation transmissivity, comprising a pluralityof rotatably mounted radiation-blocking members, each of said membershaving at least one portion which is substantially opaque, and means forrotating said radiation-blocking members, said radiation-blockingmembers, when rotated, being adapted in at least one angular position tosubstantially block the passage of radiation through said panel, and ina plurality of other, selectable, angular positions, to provide aplurality of differing radiation transmissivities, characterized by aplurality of substantially transparent tubular cells, at least one ofsaid radiation-blocking members being mounted in at least some of saidtubular cells, and means for rotating said radiation-blocking membersinside said tubular cells.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in connection with certain preferredembodiments with reference to the following illustrative figures so thatit may be more fully understood.

With specific reference now to the figures in detail, it is stressedthat the particulars shown are by way of example and for purposes ofillustrative discussion of the preferred embodiments of the presentinvention only, and are presented in the cause of providing what isbelieved to be the most useful and readily understood description of theprinciples and conceptual aspects of the invention. In this regard, noattempt is made to show structural details of the invention in moredetail than is necessary for a fundamental understanding of theinvention, the description taken with the drawings making apparent tothose skilled in the art how the several forms of the invention may beembodied in practice.

In the drawings:

FIG. 1 is a perspective view of a fully assembled panel according to theinvention;

FIG. 2 illustrates a first arrangement for mounting the panel on thepurlins of a roof structure;

FIG. 3 shows a different type of clamping rail;

FIG. 4 shows a second arrangement for mounting the panel on the purlinsof a roof structure;

FIG. 5 shows a first profile of the cells of the panel member accordingto the invention;

FIGS. 6 to 8 represent other possible profiles of the cells;

FIG. 9 is a perspective view of a preferred embodiment of theradiation-blocking member according to the invention;

FIG. 10 is an end view of the radiation-blocking member of FIG. 9,located inside a cell;

FIG. 11 is a perspective view of another embodiment of theradiation-blocking member;

FIG. 12 is a perspective view of yet another embodiment of theradiation-blocking member;

FIG. 13 is a variant of the radiation-blocking member of FIG. 12;

FIG. 14 is an end view of still another embodiment of theradiation-blocking member;

FIG. 15 is an exploded view of a panel according to the invention;

FIG. 16 is a perspective view, to an enlarged scale, of a portion of theassembled drive mechanism;

FIGS. 17 and 18 are perspective views illustrating a different means forrotating the radiation-blocking members;

FIGS. 19a-19 d schematically show different limit positions of theradiation-blocking member;

FIG. 20 is an elevational view of the panel of a further embodiment,including a variant of the radiation-blocking member of FIG. 9;

FIG. 21 is an exploded view of the embodiment of FIG. 20;

FIG. 22 is a perspective view of part of the panel, showing the motor,the plurality of gearboxes and the drive shaft;

FIG. 23 is a view of the gearbox in cross-section along planeXXIII—XXIII in FIG. 24;

FIG. 24 is a top view of the gear box;

FIG. 25 is a view of the gearbox in cross-section along plane XXV—XXV inFIG. 24;

FIG. 26 is a perspective view of the gearbox as cross-sectioned in FIG.23;

FIG. 27 is a perspective view of the coupling as seen from the side ofthe drive fingers, and

FIG. 28 represents a side view showing the mechanical assembly asclamped onto the panel.

DETAILED DESCRIPTION

Referring now to the drawings, there is seen in FIG. 1, representing aperspective view of a complete panel according to the invention, a panelbody 2 with a substantially planar top surface, and comprised of aplurality of cells 4. Advantageously, cells 4 are parts of an integral,transparent extrusion of such plastic materials as polycarbonate, PMMAor PVC, although it would be possible to produce a panel by extrudingsingle cells and joining them side-to-side by one of the known methods(cementing, ultrasonic welding, etc.) to form a complete panel body 2.The upper, sun-facing surface of panel body 2 is advantageously given aper se known treatment to make it UV-resistant. Optional cross-sectionsof cells 4 will be discussed further below.

The term “light,” as used in the description, is meant to include notonly the spectral range of visible light, but also ranges ofelectromagnetic radiation below and/or above that spectral range.

Inside cells 4 there are rotatably mounted light-blocking members 6, thepurpose of which is to substantially block the passage of light in oneangular position, while providing a plurality of different lighttransmissivities in a plurality of other, angular positions. Possibleconfigurations of light-blocking members will be described furtherbelow. Rotation of members 6 is effected by a mechanism to be explainedfurther below.

Further seen is an electric motor 8, advantageously a 12 V, d.c. gearmotor, mounted by means of two brackets 10 on a casing comprised of alower member 12, an upper member 12′ and a cover plate 14, which in FIG.1 is partly cut away to reveal part of the mechanism to be describedfurther below.

The rear end of panel body 2 is closed off by a plastic or metal molding15. The first and last cells of panel body 2 do not necessarilyaccommodate light-blocking members 6 because, as will be shown (FIG. 4),in some embodiments the first and last cells serve for mounting thepanel on the purlins of a roof structure.

As, again because of the extrusion process, the width of panel bodies 2is limited, while no such limitations obtain regarding length, roofs arecovered by cutting panel bodies to the required length and attachingthem in juxtaposition to the purlins of the roof structure. To this end,the panels have to be joined side-to-side in a way that will providemechanical strength and will also be waterproof.

Two of many different solutions to this problem are clearly shown inFIGS. 2-4. In a first embodiment (FIG. 2), panel body 2 is provided withflanges 16 extending along both of its longitudinal edges, the insidesurfaces of which flanges are saw-toothed. There is also provided anextruded, hollow, winged aluminum rail 18 between the two wings of whichfit the empty cells 4′ of the two adjacent panel members 2, includingtheir respective flanges 16. After rail 18, with the adjacent panelmembers 2 in position as shown, has been fixedly attached to purlins Pof the roof structure by means of screws 20, a plastic, U-shapedclamping rail 22 having matching saw-toothed wings 24 is pushed overflanges 16 of adjacent panel members 2, providing a strong clampingforce. For even greater rigidity, instead of plastic rail 22 it ispossible to use an appropriately shaped aluminum rail 26 (FIG. 3).

Another solution is illustrated in FIG. 4. Here, an aluminum extrusion28 is introduced into empty cell 4′, filling its entire longitudinalextent and imparting to it mechanical strength. Two more profiles areused: a trough-like, bottom profile 30 which fits the rounded undersideof cells 4, and a two-winged, top profile 32 which rests on the uppersurface of panel members 6 and, with the aid of screw 20, forces the twoadjacent panel members 6 (of which only one is shown) against purlin P.

Cells 4 can have various cross-sectional shapes, such as the escutcheonshape of FIG. 5, a more elaborate form of which is provided along therounded portion of its inner surface with prism-shaped serrations 34which have both an aesthetic and an optical effect. The aesthetic effectis twofold: the longitudinal lines produced are pleasing in themselves,and the serrations also hide the “innards” of the cells, in particular,scratches and wear marks that would be produced on a smooth insidesurface by the rotation of light-blocking members 6. Optically speaking,the prismatic serrations produce a softer, diffused light. A secondversion of this profile is provided with another layer 36 below the topsurface of panel body 2, for improved thermal insulation. In all cells 4the internal height advantageously exceeds the internal width, so thatflexing of the panel will not cause jamming.

FIG. 6 shows a rectangular profile of cells 4, in which panel body 2 hastwo planar surfaces.

FIG. 7 shows a cell 4 with a circular profile. Panel body 2 of thisembodiment also has two planar surfaces.

FIG. 8 is another escutcheon-type profile, with a wavy top surface.

Light-blocking members 6, as already mentioned, are rotatably mounted incells 4 and, their surfaces having a substantially opaque portion, theangular position of this portion inside cell 4 determines the lighttransmissivity of the cells which, by controlling this position, maythus be controlled between a minimum and a maximum, which depends on thesky and/or the position of the sun.

A preferred embodiment of light-blocking members 6 is shown in FIG. 9.The profile, reinforced by a horizontal and a vertical rib 37, 37′respectively, is approximately semi-circular, subtending an angle ofslightly more than 180°. Top surface 38 is substantially planar and isrendered opaque by such known means as painting, coating with an opaquefilm, or the provision of an opaque plastic layer applied bycoextrusion. Top surface 38 is delimited laterally by two bead-likeedges 40 which project beyond the semi-circular lower surface 42. Every500 to 1000 mm, depending on the total length of cells 4, the edges 40are provided with two notches or recesses 44, one opposite the other,into which are sprung plastic rings 46. It is these rings that serve assupporting elements which carry members 6 inside cells 4 and thatconstitute the only contact with the bottom of cell 4, as is clearlyseen in FIG. 10. The advantage of this kind of mounting of members 6 isthe insensitivity of members 6 to the flexure of the panel betweenpurlins, due to snow or wind loads. Up to a surprisingly high degree,such flexures will not interfere with the rotation of members 6. Thering mounting of members 6 in fact ensures trouble-free operation ofpanels having a length of 12 meters and more.

A variant of the light-blocking member of FIG. 9 is shown in FIG. 11,the difference residing in the fact that the profile portion 45 abovethe horizontal rib 37 is dovetail-shaped. Another difference is seen inring 47, which is now half split, the split portion being provided withlegs 48 which abut against surface 38. The advantage of ring 47, ascompared to ring 46, is that while rings 46 can be applied only at theends of member 6 and have to be slid along the latter for a considerabledistance (members 6 may be as much as 12 meters long), rings 47 can beopened by elastic deformation and can be quickly snapped into theirrespective recesses 44 without having to be slid along member 6.

Another embodiment of the light-blocking member 6 is seen in FIG. 12,consisting of a central rod 50 and two vanes 52. Rod 50 is supported atboth ends and vanes 52 rotate inside cell 4. While for shortlight-blocking members as required, e.g., in windows or skylights, thisembodiment needs supports only at its end, longer members of this typemust also be supported at one or more points along their longitudinalextent.

A variant of the light-blocking member of FIG. 12 is seen in FIG. 13, inwhich vanes 52 are not solid, but consisting of narrow strips 54 or evenbristles. An arrangement like this would reduce the disturbing effect ofpanel flexure.

Yet another embodiment of light-blocking member 6 is represented in FIG.14. The member 6 is in the form of a plastic tube 56 of circularcross-section. About half the circumference of tube 56 is renderedopaque by painting, coating with an opaque film, or the provision of anopaque plastic layer applied by coextrusion.

In the following, a detailed description will be given of the mechanismdriving light-blocking members 6.

FIG. 15 is an exploded view of the drive mechanism. Power flow is quitesimple: motor 8 drives one of a plurality of gears 58 via a coupling60A, 60B. Each one of gears 58 is mounted on the first member 62A of a3-member Oldham coupling (a coupling extremely tolerant of lack ofalignment between input and output shafts). All gears 58 mesh with alower rack 64 and an upper rack 64′, each of which is slidably seated ingrooves 66, 66′ respectively, provided in lower and upper casing members12, 12′ respectively. (Although one rack 64 would do, a pure torque,i.e., a force for rotation without lateral components, requires tworacks.)

When the gear directly driven by motor 8 rotates, it causes racks 64,64′ to slide in opposite directions in their respective grooves 66, 66′,thereby rotating the rest of gears 58. Via second coupling member 62B,first member 62A rotates third member 62C, the output end of which isshaped to fit the cavities of light-blocking member 6 and thus rotatethe latter.

Referring now also to FIG. 16, there is further seen a bearing wall 68fixedly mounted between lower and upper casing members 12, 12′ andprovided with holes 70 which serve as bearings for the shafts of firstcoupling members 62A. Third coupling members 62C are supported in cells4 by the first of rings 46.

Also seen is a split wall 72, 72′ (FIG. 15), which, as is clearly seenin FIG. 16, serves to maintain the integrity of each coupling ascomprised of members 62A, 62B, 62C by preventing member 62C fromdisengaging from member 62B. The semi-circular recesses 74 do not serveas bearings for collar 76 of third coupling member 62; in fact, for thecoupling to accommodate unavoidable deviations of alignment, thediameter of recesses 74 must be much larger than the diameter of collar76.

Further seen in FIG. 15 and, to better advantage, in FIG. 16, are rings78 which have a slightly tapered bore and, when pushed onto the slotted,slightly tapered hub 80 of gears 58, clamp the latter onto shaft 82 ofgears 58.

Also seen in FIG. 16 are grooves 84 for rubber cords to act as sealswhen the assembled mechanism is mounted on panel body 2 (see FIG. 1).Similar grooves are obviously also provided in the upper casing member12′.

FIG. 15 also shows two limit switches 86, 86′ which define the extremesof the rack movement and, thus, of the rotation of light-blockingmembers 6. The limits of this rotation will be discussed further below.It will be appreciated that limit switches 86, 86′ could also beintegral components of gear motor 8.

FIGS. 17 and 18 illustrate another means for rotating the light-blockingmembers 6, which means, although conceived for use with thelight-blocking member shown in FIG. 12 or 13, could also be modified foruse with the above-described rack and gear mechanism. Using the samespring collet means that served to fixedly mount gears 58 (FIG. 16) oncoupling member shaft 82, levers 88 (FIG. 17) are attached to shafts 50of vanes 52 in FIG. 12, each lever 88 being provided with a pin 90. Abar 92 (FIG. 18) with appropriately spaced and sized holes is slippedover all pins 90 and when one of levers 88 is coupled to motor 8, isrotary motion is transmitted to all levers 88 and thus to all vanes 52.

In the following are discussed the range and control of the rotationalmovement of light-blocking members 6.

Starting, as schematically shown in FIGS. 19a-19 d, from the position offull opacity in which the opaque surface 38 of light-blocking member 6is substantially parallel to the surface of panel body 2, member 6 islimited to an angular range of rotation of 90° in both the clockwise andcounter-clockwise senses. These limits are enforced by limit switches86, 86′ tripped by rack 64 (FIG. 15). Setting out from the blockingposition (FIG. 19a) and rotating in the clockwise sense, surface 38sweeps a first quadrant of the celestial hemisphere and is stopped bylimit switch 86 in the position shown in FIG. 19b, in which it isperpendicular to the panel surface, i.e., for maximum transmissivitywhen the sun is at its highest point. In order to sweep the secondquadrant, the sense of rotation must be reversed, with member 6returning and passing through the opaque position (FIG. 19c), afterwhich the second quadrant is swept, with member 6 being stopped by limitswitch 86′.

Another embodiment of the panel according to the invention isillustrated in FIGS. 20-28. Panel body 2 is substantially identical withthat of the previous embodiment, with cells 4 being of the rectangulartype shown in FIG. 6. Light-blocking members 6 are of the type shown inFIG. 9, but may also be of an alternative design, also shown in FIG. 20:fully tubular, with an integral diametric partition 39 produced from anopaque plastic material by co-extrusiion with the transparent tubularpart. Mounting of panel body 2 on the roof purlins is analogous to theprocedure explained in conjunction with the previous embodiment.

FIG. 21 illustrates the power flow whereby the rotary movement of anelectric motor is transmitted to the light-blocking members. There isseen an electric gear motor 8 which, via two gears 94, 96 drives aslotted drive shaft 98 that extends along the entire panel width, asseen in FIG. 22. Located inside a gearbox 100, of which there is one foreach cell 4, and keyed to shaft 98, there is provided a worm 102engaging a worm gear 104, equally located in gearbox 100 and keyed toshaft 106 of coupling 108. The latter constitutes the link between themechanism described in the aforegoing and the light-blocking member 6.

It will be noticed that coupling 108 is much simpler than thethree-member Oldham coupling 62A, 62B, 62C of FIGS. 15, 16 of theprevious embodiment. The Oldham coupling, which, as was explainedearlier, is extremely tolerant of misalignment between input and outputshafts, was needed to take care of the variations, unavoidable inplastic extrusions, of the distances between cells 4. In the presentembodiment, this problem is solved by mounting the one-piece couplings108 in gearboxes 100 that are rendered “floating” by means of slots 110which provide them with one degree of freedom in translation along arail 112, thus permitting each gearbox 100 and thereby, each coupling108, to find its proper position relative to the respective cell 4. Rail112 is part of an aluminum profile 114 that accommodates the entiremechanism, including motor 8 attached to profile 114 by means of abracket 115. Panel 2 is tightly clamped between profile 114 and anotherprofile that also serves as cover plate 116.

FIGS. 23-26 represent gearbox 100 and its associated components. Seen isworm 102 slidable along, but driven in rotation by, shaft 98 by means ofa key 118 (FIG. 23). Worm 102 engages worm gear 104, which is keyed toshaft 106 of coupling 108. Shaft 106, as can be seen in FIGS. 23 and 26,is mounted in appropriately located and sized bores 120 in gearbox 100(FIG. 21). Strictly speaking, worm gear 104 should be of the helicaltype, with the helix angle o its teeth corresponding to the lead angleof worm 102. While for maximum efficiency and service life, this isindeed the appropriate solution, considering the fact that requiredspeeds are very low and forces are relatively smal, simple spur gearsshould also do. Since all transmissiion components (except shaft 98) areadvantageously designed as plastic moldings, extraction, from the mold,of a helical gear would greatly complicate the mold by demanding anadditional mechanism to produce the required helical extractionmovement.

Shaft 106 ends in a flange 122 which is relieved to a depth of abouthalf its thickness for over about three-quarters of its circumference.Into this relieved portion projects a ring segment 124 which is anintegral part of gearbox 100 and serves as a stop as well as a referencepoint for purposes of assembly of the panel unit. Further seen in FIGS.23, 24, 26 and especially in the perspective view of FIG. 27, are drivefingers 126A, B, C, D which are integral parts of coupling 108 and areconfigured to enter the spaces defined by ribs 37, 37 in FIG. 21 anddrive light-blocking members 6 (FIG. 21). For use with the cylindricalvariant of light-blocking member 6 shown in FIG. 20, the shape of drivefingers 126 must obviously be modified.

FIG. 28 is a side view showing the lower end of panel 2, onto which areclamped profiles 114 and 116 which, between them, accommodate the entiremechanism, including motor 8. Waterproofing is ensured by means of aseal 128 located in a groove in cover plate 116 and extending along theentire width of panel 2.

This embodiment, too, may have limit switches defining limit positions,with the switch body attached to a stationary part of the mechanism, andthe switch being tripped by a moving part thereof.

Obviously, light-blocking members 6 can be stopped at any angularposition, also between the limit positions defined by the limitswitches, by controlling member 8. This can be done either manually orautomatically. Manual control is effected by operating a spring-loaded,polarity-reversing pushbutton. Also required is a power supply includinga voltage stabilizer and a thermal fuse to protect motors 8. To obtainsatisfactory automatic control, it is best to use a stepping motorcontrolled by a microprocessor working with a program including allparameters involved in the proper operation of the panels, such aslimits of rotation in the clockwise and counter-clockwise senses(thereby eliminating the need for limit switches), opening oflight-blocking members 6 as a function of the prevailing light as sensedby photodetectors, dimming of artificial illumination in dependence ofnatural light entering through the panels, stopping motors in case ofoverload, etc.

Clearly, the user can always override the program or introduce whateverchanges are desired. The program can also be designed to switch off thesystem on weekends or during vacations.

The panel according to the invention will operate in all positions:horizontal, vertical, slanted, even slightly arched.

While the above-described drives are indeed preferred, other types ofdrives are also possible, e.g., chain or timing-belt drives.

Although in the foregoing the term “manual” was meant to refer to themanual activation of gear motor 8, it will be appreciated thatembodiments are envisaged in which the panel according to the invention,instead of, or in addition to, being driven by the gear motor, can alsobe operated manually.

I claim:
 1. A panel of controllable radiation transmissivity,comprising: a plurality of rotatably mounted radiation-blocking members,each of said members having at least one portion which is substantiallyopaque, and means for rotating said radiation-blocking members, saidradiation-blocking members, when rotated, being adapted in at least oneangular position to substantially block the passage of radiation throughsaid panel, and in a plurality of other, selectable, angular positions,to provide a plurality of differing radiation transmissivities,characterized by a plurality of substantially transparent tubular cells,said radiation-blocking members being mounted in at least some of saidtubular cells, and means for rotating said radiation-blocking membersinside said tubular cells.
 2. The panel as claimed in claim 1, whereinsaid plurality of tubular cells is part of an integral plasticextrusion.
 3. The panel as claimed in claim 1, wherein said tubularcells have an escutcheon-shaped cross-section.
 4. The panel as claimedin claim 1, wherein said tubular cells have a rectangular cross-section.5. The panel as claimed in claim 1, wherein said tubular cells have acircular cross-section.
 6. The panel as claimed in claim 1, wherein saidtubular cells are provided with at least one additional layer below thetop surface of said panel for improved thermal insulation.
 7. The panelas claimed in claim 1, wherein said radiation-blocking members are inthe form of tubular members, each defined by a substantiallyhalf-cylindrical portion and a substantially planar portion.
 8. Thepanel as claimed in claim 7, wherein said substantially planar portionis substantially opaque, while said half-cylinder is substantiallytransparent.
 9. The panel as claimed in claim 7, wherein said tubularmembers are provided with at least one reinforcing rib.
 10. The panel asclaimed in claim 7, wherein the longitudinal edges of said planarportion are provided with spaced-apart pairs of recesses, the recessesof each pair being located one opposite the other.
 11. The panel asclaimed in claim 7, wherein said radiation-blocking members are providedwith supporting elements.
 12. The panel as claimed in claim 11, whereinsaid supporting elements are in the form of a plurality of rings of anoutside diameter larger than the width of said tubular members, butsmaller than the width of said tubular cells, which rings aredistributed substantially uniformly along said members, each ring beingretained at its location by being sprung into a pair of said recesses,whereby said rings carry said members inside said tubular cells andconstitute the only contact with said tubular cells.
 13. The panel asclaimed in claim 12, wherein said rings are split, facilitating theirmounting on said radiation-blocking members.
 14. The panel as claimed inclaim 1, wherein said radiation-blocking members are in the form of twosubstantially co-planar vanes attached to either side of a central rod.15. The panel as claimed in claim 1, wherein said radiation-blockingmembers are in the form of substantially cylindrical tubes, each havinga substantially planar, substantially diametrically located partitionwall.
 16. The panel as claimed in claim 15, wherein said partition wallis substantially opaque, while said cylindrical tubes are substantiallytransparent.
 17. The panel as claimed in claim 1, wherein said means forrotating said radiation-blocking members is at least one electric gearmotor.
 18. The panel as claimed in claim 17, wherein said motor iscoupled to a gear wheel which, when rotated by said motor, is adapted todrive one of said radiation-blocking members.
 19. The panel as claimedin claim 18, wherein each of said radiation-blocking members of saidpanel is in a drive connection with a gear wheel, all gears wheels ofall of said members being in mesh with at least one rack guidedlyslidable in a casing of said panel, wherein said gear wheel coupled tosaid motor, when rotated, causes said rack to slide, thereby setting allother gear wheels rotating.
 20. The panel as claimed in claim 18,further comprising at least one limit switch actuatable by said at leastone rack in order to define one limit position thereof.
 21. The panel asclaimed in claim 1, wherein said means for rotating saidradiation-blocking members is an electric stepping motor.
 22. The panelas claimed in claim 21, further comprising a drive shaft driven by saidelectric stepping motor.
 23. The panel as claimed in claim 21, whereinsaid drive shaft extends along the entire width of said panel.
 24. Thepanel as claimed in claim 23, wherein said drive shaft is provided witha key slot extending along its entire length.
 25. The panel as claimedin claim 24, wherein said slotted drive shaft passes through, and is ina drive connection with, a plurality of worms of worm gears and allowssaid worms one degree of freedom in translation.
 26. The panel asclaimed in claim 25, wherein said worm gears are mounted on the inputshaft of a coupling, the output side of which is configured to enter anddrive at least one radiation-blocking member.
 27. The panel as claimedin claim 1 wherein said means for rotating said radiation blockingmembers are in gearboxes floatingly mounted on a rail of a profile. 28.A panel of controllable radiation transmissivity, comprising: aplurality of substantially transparent tubular cells; a plurality ofradiation-blocking members with each having at least one portion whichis substantially opaque, and said radiation-blocking members beingpositioned within said transparent tubular cells; and a drive mechanismwhich is in driving communication with said radiation-blocking members,and said radiation-blocking members being rotatably mounted within saidtubular cells such that said radiation-blocking members rotateinternally within said tubular cells upon activation of said drivemechanism, and when rotated, said radiation-blocking members areadapted, in at least one angular position, to substantially block thepassage of radiation through said panel, and, in a plurality of other,selectable, angular positions, to provide a plurality of differingradiation transmissivities.
 29. The panel of claim 28, wherein saidplurality of tubular cells form part of an integral plastic extrusion.30. A panel of controllable radiation transmissivity, comprising: aplurality of substantially transparent tubular cells in side-by-sideabutment; a plurality of radiation-blocking members with each having atleast one portion which is substantially opaque, said radiation-blockingmembers being rotatably received within said transparent tubular cellsfor rotation of said radiation-blocking members inside said transparenttubular members; means for rotating said radiation-blocking membersinside said tubular cells, and said radiation-blocking members, whenrotated, being adapted in at least one angular position to substantiallyblock the passage of radiation through said panel, and in a plurality ofother, selectable, angular positions, to provide a plurality ofdiffering radiation transmissivities.
 31. The panel of claim 30, whereinsaid plurality of tubular cells is part of an integral plasticextrusion.